Aminoalkyl phosphonates and preparation thereof



3,322,863 AMHNUALKYL PHQSPHONATES AND PREPARATEON THEREUF Warren J.lilahourn and Elvis E. Jones, Lake Jackson,

Tern, assignors to The Dow Chemical Company, Midland, Micln, acorporation of Delaware No Drawing. Filed Sept. 9, 1963, Ser. No.307,285 7 (Ilaims. (Cl. 260-944) This invention relates to aminoalkylphosphonate compounds, to the preparation of such compounds, and to themanufacture of useful compositions containing aminoalkyl phosphonates.More particularly, the present invention relates to aminoalkylphosphonates (and plastic materials containing such aminoalkylphosphonates (formed by the reaction of (1) an imidazolidine compound(containing a 5-membered saturated heterocyclic ring with two nitrogenatoms) and (2) a diester of phosphonic acid (such as a dialkylphosphite).

The preparation of diethylami-nomethyl phosphonic acid diet-hyl ester bythe reaction of tetraethyl methylenediamine and diethyl phosphite isdiscussed in US. Patent 2,635,112 to Felds. In this process, however,the diamine molecule is cleaved during the reaction and diethylamine isobtained as a lay-product.

The compounds of the invention are prepared according to the reaction:

wherein R represents a lower alkyl group of from 1 to 4 carbon atoms(such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyland t-butyl), each R group may be the same or different and represents ahydrogen atom or an R group (preferably both R groups are hydrogenatoms) and R R and R are independently selected from the groupconsisting of the hydrogen atom, the phenyl groupand an alkyl group offrom 1 to 6 carbon atoms. Typical preparative reactions of dialkylesters of phosphonic acid and substituted imidazolidines include thefollowing:

( represents the phenyl group, -C H 3,322,863 Patented May 39, 1967Other representative R and R groups include npentyl, i-pentyl andn-hexyl. A preferred subclass 0 compounds is represented by the formulaR0 0 R1 H R0 R0 I I I PCNCO-NHz RO/ l tz R0 o where R, R R and R are aspreviously defined.

From the foregoing illustrative reactions, it is clear thatunsymmetrically substituted imidazolidines (those which containdifferent substituents in the 4 and 5 positions) can lead to twodiiferent products, depending upon which nitrogen-carbon bond of theirnidazolidine cleaves. Ordinarily, both products are formed and areseparated from the reaction mixture by vacuum distillation. In apreferred embodiment of the invention, the imidazolidine reactant issuch that all of the R groups are the same,

by several known methods. One convenient method involves thecondensation of an alkylene diamine with an aldehyde, as shown byAcheson in Heterocyclic Compounds (1960) on pages 265-266. The2,2-dialkylimidazolidines may be obtained by reacting the correspondingketone with an ethylenediamine of the formula wherein R is as previouslydefined in reaction (I).

The process by which the arminoalkyl phosphonate compounds are preparedis carried out by mixing stoichiometric amounts of the imidazolidinereactant and dialkyl ester of phosphonic acid P-H wh rein R is aspreviously defined at temperatures of from about to 65 C. (preferablyfrom to 50 C.) and then separating the product by distillation of thevolatile components. While essentially equi-molar amounts of dialkylester of phosphonic acid and imidazolidine compound are preferable,about a ten percent molar excess of either reactant may be tolerated inthe reaction mixture without adversely affecting the course of thereaction. The process may be carried out at any convenient pressure upto about 10 or atmospheres. The reaction is generally carried out atatmospheric pressure.

The aminoalkyl phosphonates of the invention are useful as reactivediluents for epoxy resins (e.g., diglycidyl ethers of Bisphenol A). Whencured, the solid products obtained have excellent heat distortion valuesand are fire resistant. The aminoalkyl phosphonates are incorporatedinto the epoxy resins in quantities sufficient to give from about 0.25percent to 10 percent of phosphorus based upon the total weight of thecured product. Amounts of phosphorus of from about 1.5 percent to 2.0percent by weight are sufficient to impart self-extinguishing propertiesto the cured resins. (Self-extinguishing properties are evaluatedaccording to ASTM D-635-56T.) Amounts of aminoalkyl phosphonate of fromabout 5 percent to 70 percent (preferably 20 to 50 percent) by weight(based on the total weight of the cured composition) may be used. Otherexamples of suitable epoxy resins with which the aminoalkyl phosphonatesof this invention can be combined are given in US. Patent 3,078,271(especially columns 5-14) to De Groote. Commercial resins such as D.E.R.332, obtained from The Dow Chemical Company, are very suitable. Themixtures of epoxy resin and aminoalkyl phosphonates form curablecompositions which can be cured with conventional catalysts such asamines (trialkylamines, ethylenediamine, etc.) or with acids oranhydrides (such as phthalic acid or phthalic acid anhydride, Lewisacids, amides and the like). As shown in the examples, the aminoalkylphosphonates themselves cause some curing of the epoxy resins. The epoxyresin composition may contain other reactive diluents as well as inertfillers and binding or cross-linking agents.

The following examples are submitted for the purpose of illustrationonly and are not to be construed as limiting the scope of the inventionin any way.

Example I ca cn o 0 H 2 P a M) 011-011 0 a N 5N 11 ca cr1 o 9 H F P d Ncn ca Nllgf I 014 014 0 CH5 Into a reaction vessel equipped with astirrer, thermometer and reflux condenser was added 172 grams (2 moles)of Z-methylimidazolidine and 276 grams (2 moles) of the diethyl ester ofphosphonic acid (diethyl phosphite) at 25 C. Upon mixing, thetemperature fell to 17 C. and then rose to 37 C. after one hour. Thereaction was allowed to continue for an additional six hours, duringwhich time the temperature varied from about 30 to C. After removing thevolatile co p e t Q16 product was analyzed and the index of refractiontaken. The product was a light yellow, viscous oil soluble in petroleumether and water. The index of refraction at 25 C. (Na D line) was1.4603. Analysis of the product gave the following results (all figuresare percent by weight).

Calculated Found (Percent) (Percent) c11 c1-1 o 0 H2 H2 II P a \i c 14CH} CH5CH2O\0 on; H n 1 N ca ca nu c11 cu o Into a reaction vesselequipped with a thermometer, stirrer and reflux condenser containing1,100 grams (11 moles) of 2,2-dimethylimidazolidine was added dropwise1.380 grams (10 moles) of the diethyl ester of phosphonic acid (diethylphosphite). The temperature rose to C. and the remainder of the diethylester of phosphonic acid was added after the temperature fell to about30 C. After three hours, the temperature was 39.5 C. and after sixhours, the temperature fell to 27 C. Volatilecomponents were removed byvacuum distillation (0.5 mm.) and the product (the[l-(2-aminoethylamino)-1- methylethyl]diethyl ester of phos-phonic acid)Was filtered giving 2,267 grams of a clear, water white, slightlyviscous product soluble in ethyl ether, acetone and water.

from Example II were added to commercial epoxy resin (diglycidyl etherof Bisphenol A; epoxide equivalent weight of 178) formed by reacting twomoles of epi- Calcumed Found chlorohydrin with one mole of Bisphenol A.The mixtures (Percent) (Percent) were cured in the presence of methylenedianiline catalyst by mixing the constituents at 85 degrees C., curingat 3-5; 5%; room temperature for 18 hours and then post-curing at 11:7611:62 165 degrees C. for 4-5 hours. The products formed were 3:63 33*self-extinguishing, had good heat distortion values and had excellentphysical strength characteristics. The con- The2,2-dimethylimidazolidine was prepared by reactcentrations of diluent inepoxy resins as ing 3 moles (174 grams) of acetone with 4 moles (240Well as some of the Important Phy tests are grams) of ethylenediamine atabout 0 C f r h 1f marized in Table II. In each compos1t1on,the totalamount hour. After removal of the water formed in the reaction, of p yresin to Which the other ingredients Were added2,2-dimethylimidazolidine was separated from the re- 15 amounted to 174grams and the amount of methylene action mixture by distillation underreduced pressure. dianiline used was 34.2 grams.

TABLE II Grams of- CII3CH2O 0 CH3 H Percent of [I Weight of Heat IzodImpact Compression Percent Arc Tensile PC-NCH2CH2NH2 P in CuredDistortion Strength Strength Elonga- Resistance Strength Composition F.)(It.-lb.-/in.) (p.s.i.) tion ($00.) (p.s.i.) CHaCHzO CH3 (Per 174 GramsEpoxy Resin) 29. 5 1. 65 271 0. 21 18, 945 4. s 11 7, 463 0 1.82 272 0.22 19, 112 4. 0 10 6, 016 36. 9 2.00 270 0. 32 16, 407 s. s s 7, 940 40.6 2. 17 265 0. 37 19, 770 9. 5 s s, 562

Example III The heat distortion value is the temperature F.) at To anepoxy resin (diglycidyl ether of Bisphenol A WhlCh the test specimenfirst begins to deform. Izod 1mwith an epoxide equivalent Weight of 178formed by pact strength we measure of the ability of a material toacting about two moles of epichlorohydrin with one mole Wlthstand aapidly applied load and 1s the force required of Bisphenol A) was addedvarying amounts of the [1-(2- to break a notched test Specimen 1131118 yswlnglng aminoethylamino)-1-methylethyl]-diethy1 ester of phostestpendulum. The values are expressed in foot-pounds phonic acid fromExample II. The epoxide equivalent per inch of notch. Compressivestrength is the compresweight is the molecular weight of the resindivided by the sion load in pounds at the yield point of a specimennumber of reactive epoxide groups in the molecule. The 40 divided by thecross-sectional area of resisting surface. amounts of aminoalkylphosphonate added and the tensile Elongation measures the increase inlength of a measstreflgth 0f the curfid Products glven lI1 Ta'b1e Theured strip of material when stretched to the breaking point RS111 sCured Wlthout an addltlonal g agent for and is expressed in terms ofpercentage increase of the 1116 hoursnzg 1801p t p i g f, f I;1 for 2original length of the test specimen. Arc resistance is a Ours a} In ore ermme 6 Op measure of the resistance of the surface of a material tocentrat1on of phosphonic acld ester to be used durmg the the a Sa 6 of a1 t h t 1 t d curing cycle (the theoretical equivalent weight based p Sg n e ec are W en We point 6 66 m es on reactive hydrogen atoms is /3 ofthe formula weight). r placefi upon two Points on the same surface ofmate For convenience the actual equivalent weight was set rial and 1srecorded as the lapsed time in seconds before at h 1f f h f l i h sinceat i propor. the arc ceases to travel in the air and begins to traveltion, optimum properties are obtained. along the surface of the testmaterial.

TABLEfI Grams of- CIIaCHzO 0 CH3 II H I Percent Tensile PCNO H2O HzNIIzPhosphorus Percent Strength (1; in Cured Elongation (p.s.i.) CH3CII2O HaProduct Combined With 174 Grams of Diglycidyl Ether of Bisphenol AExample IV We claim as our invention: Varying amounts of 1. A compoundof the formula OH3CHO\$]) 0H H RO\|C| 1'1, 111 1'1 1'1 PCNCH2CI-I2NH1PCN(I3(I3N-R3 CHSCHZO GHQ R0 2 R0 R0 "wherein each R is a lower alkylgroup, each R is independently selected from the group consisting of thehy- 565 C. stoichiometric amounts of a di(lower alkyl) ester ofphosphonic acid and an imidazolidine of the formula drogen atom and alower alkyl group, and each of R R and R is independently selected fromthe group consisting of the hydrogen atom, the phenyl group and an 5 n nalkyl group of from 1 to 6 carbon atoms.

2. A compound of the formula BO 0 R 11 RuRo n; n N a; \u l 1 c PCNCCNH2l l R1 R2 R0 R2 R0 R0 wherein each R is a lower alkyl group and each ofR0, whereln each R 1s independently selected from the group R and R isindependently selected from the group conconslstmg of the hydrogen q anda lower alkyl group sisting of the hydrogen atom, the phenyl grou and anand each of R R and R is independently selected from alkyl group of from1 to 6carbon atoms 15 the group consisting of the hydrogen atom, thephenyl 3 A compound of the formula group and an alkyl group of from 1 to6 carbon atoms.

' 7. A process which comprises reacting at a temperaoHaoHo H ture of5-65 C. essentially equimolar amounts of the PCNCH2OH2NH2 diethyl esterof phosphonic acid and an imidazolidine of l CH3CH20 R2 th formulawherein R and R are each independently selected from the groupconsisting of the hydrogen atom, the phenyl group and an alkyl group offrom 1 to 6 carbon atoms.

a N N a 4. The compound:

c CHsCHzO 0 CH3 H \II R1 R2 PCNCH2CH2NH2 CHQCHZO/ E wherein R and R areindependently selected from the group consisting of the hydrogen atom,the phenyl group and an alkyl group of from 1 to 6 carbon atoms.

5. The compound:

CH3CH2O\|0 CH3 P-CNCH2CH2NH2 CHARLES B. PARKER, Przmary Examiner.CHgOHzO H 6. A process for the preparation of aminoalkyl phos- JOSEPHBRUST Examiner phonates which comprises reacting at a temperature ofBERNARD BILLIAN, Assistant Examiner.

No references cited.

1. A COMPOUND OF THE FORMULA
 6. A PROCESS FOR THE PREPARATION OFAMINOALKYL PHOSPHONATES WHICH COMPRISES REACTING AT A TEMPERATURE OF5-65*C. STOICHIOMETRIC AMOUNTS OF A DI(LOWER ALKYL) ESTER OF PHOSPHONICACID AND AN IMIDAZOLIDINE OF THE FORMULA